The Loose Thread
by Lost in Ashes
Summary: When Sherlock is 6 years old he falls out of the tree, and finds at the bottom of it a little boy with grey skin and a worried expression. Sherlock is determined to solve the mystery of who he is and why he only appears when Sherlock is close to death. Not a crossover but heavily inspired by aspects of His Dark Materials by Phillip Pullman.
1. Chapter 1

A/N: For hitlikehammers.

Thanks to blue_eyed_1987for beta!

Chapter 1

_Everybody knows__  
death creeps in slow  
Til you feel safe in his arms  
(from O Maria by Beck)_

Sherlock pauses for a moment to catch his breath. This tree is much bigger than the ones in his garden – he's so high up now that the picnic cloth looks like a handkerchief spread out on the ground. Sherlock can pick out the yellow coloured dot that is Mummy's head, bobbing up and down as she laughs. The small dark splodge beside her is Mycroft, of course. He's pretending to read a book but Sherlock knows he's actually eavesdropping on the grownups. The high-pitched tone with which Mycroft had hissed at him, _go away Sherlock, I'm busy_ definitely meant he was trying to be subtle.

Sherlock can't understand what Mycroft finds so interesting – they're all just talking about politics and University regulations and sexual innuendo. Playing pirates is _much_ more fun.

Sherlock plucks an acorn off the branch beside him. The picnic party, he decides, is an enemy ship, skulking in green waters. He's climbed the crow's nest to spy on them – underneath him his crew is hidden by the bristling leaves.

"Fire at will!" Sherlock calls out and launches the acorn towards the picnic blanket. It lands a long way short, but Sherlock catches Mycroft's head lift up and look at the place where it fell. Sherlock looks around him for more ammunition. There isn't anything close by but at the end of the branch is a tempting little clutch of acorns.

Sherlock gets to his feet and steps out carefully onto the branch. It creaks under him, the leaves at the end of it shivering. Sherlock pauses, wondering if perhaps he ought to try another branch instead, when he hears a rustle of feathers.

The bird whooshes over his head and lands on the end of the branch. It's a starling – Sherlock can tell from the spattering of white speckles on the oily black feathers. There's something wrong with the bird's tail, the feathers crumpled, standing up at an odd angle as if something had tried to take a bite out of it. Sherlock thinks he can see the white gleam of bone poking through. If he gets a closer look perhaps he will be able to tell what sort of animal had wounded it – maybe there will be teeth marks. Sherlock gets to his knees and crawls closer down the branch. The bird cocks its head and looks at him.

That's when Sherlock catches sight of something very odd out of the corner of his eye – a flash of grey moving over the green grass below him. He looks down.

There is a boy standing directly beneath him at the foot of the tree, looking up at Sherlock. Sherlock stares. The boy seems like an ordinary child except he's the wrong colour. From his eyes, to his upturned nose, to his clothes – he's all grey, as if he's been painted with clay.

The boy bites his lip and then holds up his hands towards Sherlock, palms open, as if he's waiting to catch him. Sherlock opens his mouth to ask what the boy is doing but before he can get a word out he hears a sharp cracking sound and the branch beneath him gives way. He crashes into the branch beneath him, which knocks the breath out of him, and after a moment of hanging in dizzyingly empty space he slips backwards.

The next thing Sherlock is aware of is that there is a circle of faces looking down at him. Mummy is next to him, wringing her hands and talking rapidly. On the other side of him the little grey boy kneels in the grass, watching him.

"Wha-" Sherlock starts to say, but finds he can't draw in enough breath to finish the world. Pain stabs through him, as he tries to pull air into his burning lungs. He can feel a terrible pressure growing on his chest, as if he is being crushed by a great weight but he can't see anything on him. He tries to roll onto this side and sit up, but the pressing feeling only grows worse when he tries to move.

"Darling," Mummy says, smoothing his hair. "Don't try to move. Just lie still, help is coming and Mummy's here."

Sherlock glances back at the boy. He looks very sad, Sherlock thinks, mouth pulled downwards, small forehead creased in serious lines. Despite the graveness of his expression, Sherlock likes looking at him. There's something comfortable about his face, something that makes Sherlock feel warm deep inside, peaceful, the pain in his chest seeming to ebb away. He's never liked to be still but right now he's starting to think that lying here and doing nothing at all might be a very nice way to spend time after all.

"Sherlock, please, stay with Mummy, stay with me….." Mummy keeps talking and talking but Sherlock finds it increasingly difficult to understand the words coming out of her mouth. Her face is a blur.

The boy, on the other hand, seems to be getting clearer and clearer, as Sherlock were turning the adjustment on his microscope to focus on his face. Now he can see the faint freckles on the boy's nose, the slight crease between his eyebrows when he frowns. The single strands of hair hanging down over his forehead stand out so sharply Sherlock thinks he could count them. He can hear the boy's breath in his ears.

The boy ducks his head a little and sighs deeply, small chest rising and falling, before reaching out a hand to hover over Sherlock's cheek.

A harsh sound breaks through the hush, a discordant whooping and screeching that makes Sherlock wince. Dark shapes approach, circling around him and the grey boy before descending on Sherlock and pushing something cold and hard over his mouth and nose. Suddenly Sherlock remembers the pain from where he'd hit the branch and agony explodes through him again, so blindingly sharp that for a few minutes everything is blotted out by it.

The next thing Sherlock knows he is being carried on a long bed through the field. Up close Sherlock can see the dark shapes are men wearing paramedic uniforms and that one of them is talking to Sherlock is that carefully kind tone adults always use with Sherlock before they've had a chance to get to know him better. Mummy is running beside them, her face very white and pinched. Sherlock raises his head a little. The grey boy is also jogging after the stretcher but the medics are too fast for him - he's losing ground, slipping further and further away until Sherlock blinks and can't see him anymore.

* * *

Hospital is very boring. Sherlock is told over and over that he is Very Lucky. He's broken his leg and broken his ribs and had a tension pneumothorax where a piece of bone punctured his lung, but he'll get completely better with time. Sherlock isn't sure why they keep telling him the same thing, but remembers Mycroft telling him that adults like repetition and that it's best to humour them. It isn't like he has much choice - his chest is so achey and tight that he can't talk back.

Mummy stays with him overnight. Sherlock can't sleep in the horrible plastic-smelling hospital bed, so Mummy reads him stories until her voice becomes as scratchy and hoarse as Sherlock's.

Daddy and Mycroft arrive in the morning. Daddy gives him a long and very careful hug before Mycroft pushes him out of the way.

Mycroft's face is pale, chubby hands clenched into fists. "Are you stupid?" he asks Sherlock.

"Mycroft…" Mummy says admonishingly.

"There are twelve different ways to tell is a branch is strong enough to support your weight. Twelve. I _told_ you to memorise them. Did you not remember? Or did you just fail to apply them?"

"Now, now. I'm sure Sherlock just.." Daddy begins but Mycroft ignores him.

"Climbing trees is a childish game anyway. I grew out of it when I was _five_. You're _almost seven_. I don't understand how I can be related to someone so backward!"

"_Mycroft_!" Mummy repeats, and Daddy puts a firm hand on Mycroft's shoulder, leading him over to a chair, muttering something in his ear.

Sherlock's hands curl into fists. He wants to shout back at Mycroft but just thinking about the effort involved makes his chest hurt a lot. Mummy pulls a silly face at him behind Mycroft's back which makes him feel a bit calmer. Mycroft doesn't know _everything_.

Speaking of which….

"What …happened… to the little boy?" Sherlock asks, ignoring the stabbing pains in his chest.

"What little boy?" says Mummy.

"There was a boy….under the tree… painted in grey. He was trying…. to catch me."

Mycroft turns away from Daddy to stare at Sherlock, eyebrows rising towards his hairline. He turns to Mummy.

"Mummy," he says loudly. "I think Sherlock is broken."

"Of course he isn't." Mummy says firmly. "But you know, darling, there weren't any other children at the picnic. Just you and Mycroft."

"He was there," Sherlock insists, and tries to sit up before being reminded of how broken his chest is. "I saw him."

"Oh, well, maybe someone was just passing by," Mummy says. "We might have missed him in the confusion, mightn't we Mycroft?"

Mycroft rolls his eyes as if to say he'd done no such thing. Mummy smiles down at him, but it's the same too-wide smile she'd used when telling him about Father Christmas so Sherlock knows she doesn't _really_ believe him. It doesn't matter, Sherlock decides. He'll find the grey boy again himself, and then they'll all know the truth.

* * *

Sherlock returns home soon afterwards but is mostly confined to bed or sitting around in his chair. His plastered leg won't let him go and investigate the boy he'd seen under the tree – it won't let him do anything interesting at all. Even looking at samples on his microscope is impossible because his chest hurts when he leans forward.

It isn't as if his family doesn't try to entertain him. Mummy chatters to him about her research and sets him equations to solve, and Daddy plays him piano. Mycroft, with a pinched and long suffering expression, reads to him from the books Mummy has brought home from the library. Sherlock doesn't particularly like it when Mycroft reads, because he always sounds sarcastic and refuses to do any of the character's voices, but it is better than nothing.

"_He was a very silent man by custom. All day he hung round the cove or upon the cliffs, with a brass telescope; all evening he sat in a corner of the parlour next the fire and drank rum and water very strong. Mostly he would not speak when spoken to; only look up sudden and fierce, and blow through his nose like a fog-horn; and we and the people who came about our house soon learned to let him be. Every day, when he came back from his stroll, he would ask if any seafaring men had gone by along the road? At first we thought it was the want of company of his own kind that made him ask this question; but at last we began to see he was desirous to avoid them_." Mycroft reads nasally, as Sherlock shifts to look at the words over his shoulder.

"Oh," says Sherlock says.

"What is it?" Mycroft says, looking irritated at the interruption.

"Give me that book," Sherlock says. Mycroft hands it over with raised eyebrows and Sherlock stares at the picture on the page. The man with the peg leg and patch is clearly the seafarer and secret pirate (obvious) that the narrative was describing but Sherlock's eyes are drawn to the boy beside him. Small, with large blue eyes and a tippy-up nose. On closer inspection the resemblance isn't as strong as Sherlock had thought, but none the less it is enough to give Sherlock pause. The memory of the grey boy had been slipping away from him, like ice melting to nothing in his palm. The illustration makes image of him trickle back through his mind. He looks at the caption under the illustration. Jim Hawkins. _Jim_ doesn't fit right somehow in Sherlock's head. He tries again. Jim. Jimmy. James.

"Sherlock?" Mycroft says, and Sherlock turns back to scowl at him.

"You can carry on reading," Sherlock says imperiously. He waits until Mycroft has gone to the loo to surreptitiously tear out the page with the picture of Jim Hawkins on it, fold it up and tuck it into his pocket. When Mycroft comes back and picks the book up again he gives Sherlock a very strange look but says nothing.

It takes two months before Sherlock can limp out across the field on his crutches to the field where the picnic had happened. There is no one there, of course. Sherlock examines the grass under the tree carefully where he had fallen and where the boy must have stood, but of course there are no clues to be found. Sherlock thinks about the past two months and how often it must have rained and how the grass must have grown. He wonders how long it takes for footprints to be obscured under normal weather conditions and decides he will make a study of it one day.

Sherlock stands and listens for a moment to the wind rustling the leaves on the tree and the distant sound of sheep bleating.

"Hello," he says. There's no response. "Grey boy? Jim? James?"

Nothing. The air around Sherlock feels as balmy and indifferent as anywhere else. Sherlock bites his lip in frustration for a moment and turns away.

It's a year before Sherlock stops carrying the picture of Jim Hawkins around in his pocket and another three years before he stops making the hopeful pilgrimages to the tree. By the time Sherlock is old enough to go to school the memory has been, if not forgotten, pushed to the back of Sherlock's memory, to a quiet undisturbed corner where it gathers dust.

Then, when Sherlock is twenty years old, he sees the grey boy again.

* * *

Sherlock is lying flat on his back on the floor of his room. He has made an error of judgement. His heart is skittering in an uneven rhythm in his chest, and Sherlock can hear the beating of his own blood throbbing painfully through his veins. Above him the lights seems to fizzle and crack.

An overdose, Sherlock thinks, is a pitifully ordinary way to die. Still. At least he won't be bored for long.

It's then that Sherlock hears something close to his ear, a soft exhale of breath. Since he is, to the best of his knowledge, alone in the room, this is something of a puzzle. Carefully, painfully, Sherlock turns his head to look.

"Oh," he says. "It's you."

The grey boy isn't a boy anymore, but a young man – taller (but clearly still not very tall), face filled out but with the same unmistakeable upturned nose and smooth looking grey-washed skin. He's lying on the floor beside Sherlock, turned on one side. Their faces are level, and Sherlock feels caught by the clear softness of his gaze, pale grey flecked with black. Curious, Sherlock raises a hand, reaching to touch but the grey man shakes his head infinitesimally.

"Phone," he says. His voice is very quiet, muffled as if he were on the other side of a wall rather than inches away from Sherlock's face.

"What?"

The man's eyes turn to something behind Sherlock and Sherlock struggles onto his elbows to look. The room phone sits on the desk a few feet away.

"Too far," Sherlock says, and the man's expression shifts, jaw tightening and eyes glistening in a way that looks like pleading. Sherlock isn't much given to acts of compassion for strangers, but Sherlock finds he doesn't like seeing the look of distress on the grey man's face. Despite himself, Sherlock finds himself hauling himself up and over to the desk. He knocks the phone out of its cradle and with shaking fingers dials 999.

"There," says Sherlock thickly turning back to where the grey man had lain. "I hope you're ha-"

But the floor is empty. The grey man has disappeared. Sherlock falls back, listening to the thundering of his blood and the gabbling of the operator on the other end of the phone and curses himself for losing his grey man again.

He doesn't mention the grey man to anyone at the hospital – at best it will lead to a lecture about the dangers of abusing hallucinogenics, at worst it'll result in an admission to the psych ward. And he isn't a child anymore – he isn't naïve enough to share his reality and expect people to understand.

It isn't the drug, of course. Sherlock is sure of that, but decides to prove the matter empirically just to be sure. He runs various experiments, altering his position in the room, the quality of light, amount of sleep, diet, the dosage of the drug – but fails to summon so much as a shadow of a grey person.

Eventually Mycroft appears with the intention of interrupting his experiments and taking him into rehab. Evading him takes up so much of Sherlock's time and energy that it leaves room for little else. And then, one fateful evening, when he is in the act of giving Mycroft's minions the slip, he happens to find himself at the scene of a grisly murder and develops a new preoccupation entirely.

* * *

Sherlock is twenty nine years old when he sees the grey man for the third time. The cat burglar he's been chasing turns out not only to be more agile than Sherlock had anticipated but also carrying a concealed knife. Sherlock registers this fact at about the same time as he staggers backward in the alleyway, sliding down the wall. The wound on his thigh spatters a disturbing quantity of blood the floor. Sherlock gropes at the scarf around his neck, tugging it loose, as spots begin to dance in his vision. He is in the act of tying it around his thigh, a rather inadequate tourniquet, when he hears footsteps and looks up. The grey man stands for a moment looking down at Sherlock before crouching down in front of him. His face is thinner than when Sherlock last saw him, thin lines appearing on his forehead. He looks down at Sherlock's leg with something like resignation. Sherlock pulls at the scarf but his hands are starting to feel numb, the alleyway around him blurring.

"Tighter," says the grey man, in that same muffled distant-sounding voice.

"You could help," Sherlock gasps out, but the grey man only looks at him and slowly shakes his head.

"I'm dying," says Sherlock. "Aren't I? That's why you've come."

"Stop talking," the man says. "Tighter."

"That's why you always come," Sherlock says, rather pleased at such deductive brilliance in the face of what is probably massive blood loss. "When I'm…. on my way out. What are you, my guardian angel?"

The man glances up at him and a complicated sort of expression flashes across the man's face. He takes a short breath, and then lets it out. Sherlock feels the stream of air on his face.

"What are you?" he repeats. "James?" he tries out, but the man only stares at him gravely.

"Pull," he says. "30 seconds."

Sherlock hears the tell-tale wail of sirens in the distance, and sees the man rise and take a short step back.

"Don't," he says. "Don't go."

But the man only gives him a sad half-smile and takes another step away from him. Sherlock hears footsteps at the other side of the alley, the unmistakeable banging and fumbling of approaching paramedics. When he looks back to the place where the grey man had stood, he is gone.

Lestrade visits him in hospital a few hours later, looking harried. Sherlock observes him fidgeting at the foot of his bed through his opiate induced haze.

"I thought you'd want to know, we caught him."

"James?" Sherlock says, somehow aware that this option doesn't make sense but also unable to put his finger on why.

Lestrade blinks several times. "No – Asquith Fortender. The man who stabbed you."

"Oh, yes," Sherlock says. "Harder to catch a grey man. Tends to slip away just when you think you've got him."

Lestrade's eyebrows rise and he goes to take a frowning look at Sherlock's morphine pump. "Do they know you're an addict in here?"

"The drugs are entirely necessary." Sherlock says.

"I've heard that one before," Lestrade mutters.

"Someone has ripped a hole through my leg."

"Yeah," Lestrade says, and he looks a bit softer after that, eyes crinkling up in the same way the grey man's had. James. James, James. James? The name itself frustrates Sherlock – he has the sensation of nearly reaching a realisation only to have it wriggle out of his grip at the last moment

"I'll need time off," Sherlock says. "Won't be able to take cases for a while."

"Yeah, I thought you would," Lestrade says, looking down at Sherlock's bandaged leg.

"I need to do research," Sherlock says. "Lots and lots of research. You'll have to bring me my laptop. My keys are in my coat."

"Sherlock – I've got a job, I can't be running back and forth after you. Isn't anyone else you can ask?"

Sherlock fixes him with a piteous look of the sort he'd spent years perfecting in the mirror for occasions such as these. Lestrade sighs, and rubs a hand through his hair.

"Fine. Laptop. Anything else you need while I'm there?"

Sherlock beams at him. "I'll make you a list."

* * *

Sherlock is determined not to let the mystery of the grey man evade him one more time, but researching the matter proves more difficult than he'd hoped. He is forced to resort to the extreme measure of joining message boards frequented by ghost hunters, angel worshippers and spiritualists of various descriptions. It takes several weeks trawling through the ramblings of the delusional and the gullible before he finds something could be a lead. Or, more to the point, some_one_.

It has been a while since Sherlock has visited St Bart's hospital. The smell of corridors near the morgue is surprisingly comforting – cleaning fluid, antiseptic, formaldehyde. _Eau de autopsy_. Sherlock lingers in the corridor near the registrar's office, waiting.

It is only ten minutes before the registrar appears bustling out of the door with her lab coat flapping at her heels, her arms full of files. Sherlock springs to attention, deliberately stepping into her path.

"Excuse me,"

"Oh!" The woman starts and, as Sherlock predicted, the files tumble out of her arms onto the floor, paper spilling everywhere.

"Oh, gosh, I'm terribly sorry," Sherlock says. "Please let me help."

"Oh, no really, it's-"

"I insist," Sherlock gives the woman his most winning smile, and notes with satisfaction a blush flaming across her cheeks. He sorts the paper swiftly and efficiently, stacking the files again and handing them to the woman.

"Thank you, goodness you are awfully fast! I mean – oh, that sounded wrong. It always takes me ages to do that sort of thing and I-" the woman babbles.

"It's not a problem," Sherlock says, and looks down at her with the attentive focus that he knows people find attractive. "I don't think we've been introduced, have we? My name's Sherlock Holmes, new consultant in Paediatrics."

"Molly Hooper," says Molly.

"Molly," Sherlock repeats, in a deliberately caressing tone and pauses for a moment. The woman looks up at him, eyes wide and – yes – pupils just slightly dilated. Sherlock bites his lip a little in a parody of hesitancy.

"Listen – I know it's terribly forward of me but - would you fancy grabbing a coffee later?"

The woman's blush deepens and for a moment Sherlock wonders if she is going to spill the files again – to her credit she does not. "I'd like that," she says. "I'm on the staff list, just give me a text."

Sherlock does not, in fact, have a copy of the staff list, not being a St Barts employee. He does, however, already have Molly Hooper's number.

* * *

They arrange to meet in a café claiming to be an American-style diner down the road. Sherlock chooses it because it has large high backed leather booths rather than seats, giving them a little privacy. (If the content of the conversation he is about to have ever gets back to Mycroft he will never hear the end of it.)

Molly arrives two minutes late, looking pink and flustered but with a broad smile on her face. As she glances at the booth Sherlock notices her smile falter, a frown line appearing on her forehead.

She must have seen through his pretence somehow. Well, that will save time. At least she hasn't immediately stormed out.

"Can I get you-all something?" A waitress, making a very poor attempt at imitating a midwestern American accent, appears at their booth.

"I'll have a black coffee," Sherlock says.

"Um… tea please," Molly says. Sherlock waits until the waitress has brought their drinks, before leaning forward and beginning.

"I'm afraid," he says. "That I asked you here under false pretences, Molly. Or should I say _Mystic Mary_."

Molly looks up at him, looking startled. Then she groans.

"Oh God, not again. How did you track me down?"

"With some difficulty," Sherlock admits. "You've changed your name twice since your days on the stage and changed address four times. But there are always ways."

"Then you realise, I don't do this sort of thing anymore," Molly gets up and fumbling in her purse pulls out a couple of pounds which she slams down on the table. "Goodbye."

"Wait," Sherlock catches her by the wrist. "Please just give me ten minutes. I really need your help. There isn't anyone else I can ask."

"Let go of me," Molly says.

Sherlock drops her hand immediately but continues looking up at her with his best pleading expression. It seems to work – there is a look of pity dawning in Molly's eyes when slowly she lowers herself back into her seat.

"Ten minutes, then," she says. "And I don't know what you've been told, but I can't speak to the dead - thank God. The dead are quiet. That's why I chose to work in a mortuary."

"I don't want a medium."

Molly glances at him and then briefly at a point to his left and then back again.

"I can't tell you what happens after you die either. I don't know much more than you do and what I do know probably isn't what you want to hear."

"I don't care about that either," says Sherlock.

Molly looks at him curiously. "Then what do you want?"

"An explanation," Sherlock says. "You can't speak to the dead but you _do_ see things other people can't, don't you? Things most people wouldn't believe in?"

"Maybe," Molly says cautiously. "Why do you want to know?"

"When I was six years old, I fell out of a tree…." Sherlock tells Molly the story of his visits from the grey stranger. She listens quietly and without comment, eyes fixed on the table in front of her and face kept carefully blank.

"So, you want to know how to make these – visions – go away?" Molly asks at last, once he is finished.

Sherlock blinks at her. "Of course not. I want to find out where he is and _what_ he is. I want to talk to him."

"Oh," says Molly, and her hand shifts to cover her mouth a little too late to hide the smile pulling at it.

"Is something amusing?"

"Oh – no, not really. It's just –"

She stops, eyes wide, clearly caught with indecision about whether to tell him something. Sherlock swallows his irritation and gives her a reassuring smile.

"Go on."

"Well - I can help you with the first one. He's sitting right next to you," she inclines her head to the left of Sherlock.

Sherlock jerks around sharply to stare at the empty space beside him. There is nothing there.

"I can't see anything."

Molly sighs and picks up her teacup, taking a careful sip. "No," she says. "You wouldn't."

Sherlock rounds on her. "Explain."

Molly's eyes fix on the cup. "You know, there are some things most people are happier not knowing."

"I'm not most people," Sherlock snaps. "I need to know. Why is he here?"

"He's here because you're here." Molly says.

Sherlock grits his teeth at the non-answer. "So," he says. "I'm being – haunted?"

"Not any more than everyone is." Molly says. Her thumbnail taps against the mug for a moment before she clearly makes a decision, opening her mouth to and saying. "He's your Death."

Sherlock stares at her. "My what?"

"Everyone has a Death. It's just that usually they can't see them. Your Death is born at the same time as you, and they grow up beside you. They watch you every day of your life, and they – wait. Until it's time. Then they.."

"Murder you?" Sherlock asks.

Molly giggles. "No! Well, not really. I don't think they actually _kill_ you they just sort of – guide you into, well. Whatever comes next."

Sherlock frowns. He thinks of the grey boy under the tree standing with eyes wide and his arms outstretched. The man lying on the carpet beside him, directing Sherlock to the phone.

"He didn't seem like he wanted me to die," Sherlock says. "He was telling me to keep trying."

"Yes, well," Molly picks up the plastic wrapped biscuit by the side of her mug and rips it open. "Being Death is a job. It doesn't mean they have to like it." She takes a bite.

Sherlock turns again to frown into the empty space beside him. It looks completely ordinary, completely lacking in any indication that there is any kind of supernatural presence occupying it. He reaches out a hand into the space but all he finds is empty air.

"His name isn't James," Molly says.

"What?" Sherlock turns around to look at her.

"He told me to tell you. He hates it when you call him that. He's called John."

Sherlock breathes out. It confirms more than anything that Molly isn't lying to him – the only person who could possibly have guessed about Sherlock's name for the grey boy was Mycroft and even he was unlikely to have deduced the real reason for Sherlock's _Treasure Island _preoccupation.

"John," he repeats to himself. It has a comforting ring, causing a reverberation deep in his chest. Yes, he thinks, that's right. He considers for a moment.

"Does John want to say anything else to me?"

Molly turns to look at the empty space again, then leans forward inclining her head as if trying to listen to something very faint. Then she leans back and looks at Sherlock, an oddly thoughtful expression on her face.

"He says he thinks you're brilliant," Molly says. "He says he doesn't think people tell you that often enough."

Sherlock stares at the empty space, suddenly at rather a loss for words.

"He also thinks you're an idiot, and that people don't tell you that often enough either," she adds.

Sherlock finds himself actually smiling a little despite himself. "He's not that observant then."

Molly frowns, craning forward across the table again, then turns to look at him, her dark eyes troubled. "He says you should stop thinking about him – that it isn't your time yet. You should be focus on looking after yourself and on – on your work." She gives Sherlock a curious look. "You didn't tell me you were a detective."

"Consulting detective," Sherlock says. "Only one of my kind." He looks back to the space beside him. "Is there anything else?"

Molly shifts, kneeling up on her chair to get closer to the empty space.

"I'm sorry," she says. "Deaths are always quiet – it takes a lot of effort to listen to someone else's. I think that's all I can get for now."

They both fall silent for a moment. Sherlock angles his head towards the space where John supposedly is, trying to sense – anything. God, he thinks, this is frustrating.

"Are you OK?" asks Molly.

Sherlock shakes himself inwardly. He is here to get information, he reminds himself. It would be foolish to let an opportunity like Molly Hooper go by without making the most of it.

"You say everyone has a Death?" he asks.

"Yes. Mine is standing by the door. His name's Toby," Molly gives a little wave across the café. "He can't come any closer because-" she stops short, face suddenly flooding with colour.

"Because?"

Molly's mouth twists a little, reluctantly. "I'm going to have a long life," she says. "The closer your Death is to you…."

"The closer you are to dying." Sherlock says. "I understand." He pauses. "You told me John is sitting beside me."

"Yes," Molly gives him a wide eyed look of sympathy that Sherlock finds instantly irritating. "It's odd though," she adds. "I've never seen a Death behave the way yours does. Usually the death stays at a stable distance, they move closer by inches, over _years_. But yesterday, he was half a corridor away from you. If you'd asked me then I'd have guessed you'd live to be ninety. Otherwise I wouldn't have... well."

"Yes, quite. No point in dating a dying man." Sherlock agrees.

Molly bites her lip. "I didn't mean…"

"You did." Sherlock says. "No matter – it's irrelevant." Sherlock picks up his cooling coffee and takes a sip from it thoughtfully. "What would make a Death behave so uncharacteristically then?"

Molly shrugs. "I'm sorry – I've no idea."

Sherlock eyes her thoughtfully. "Deaths aren't all you can see, are they?"

Molly shivers slightly and pulls her mug closer to her. "No. There are other things that aren't nearly so pleasant. Nor so quiet."

"Such as?"

"Believe me when I say, you really are better off not knowing," Molly says. "It frightened the life out of me at first. I nearly ended up in a psychiatric ward."

"You weren't born like with this ability then?"

"I had childhood epilepsy," Molly says. "One day I had a fit and it just seemed to knock something loose. My mum thought it was a gift from god – hence the whole Mystic Mary thing. She thought I could make my fame and fortune giving people spiritual comfort but it didn't work that way. The things I could tell people mostly weren't what they wanted to hear."

"You have a lot of dissatisfied customers on the web," Sherlock says. "It was what clued me into the fact you might have a genuine talent. A charlatan would have told people comforting tales about their dear old Granny being surrounded by angels and shining lights. You told people the truth."

"Much good it did them," Molly says. "They always finished up looking like you do now."

"Oh? How do I look?"

"Frustrated. Sad." Molly says. Sherlock opens his mouth to contradict her, but finds he cannot. A bleeping noise goes off and Molly checks her phone.

"Sorry," she says. "I have to go. Work calls. I hope this – you know – helped."

"It did," Sherlock reaches out a hand to take hers, and gives her as sincere a look as he can manage. "Thank you, Molly Hooper."

Molly gives him a lopsided smile and gets to her feet and, with a swift nod at the empty space beside him, she leaves. Sherlock sits for a while in the empty booth sipping his cold coffee. Eventually he gets to his feet and looks at the empty seat.

"Well then," he says. "I suppose it's just you and me."

* * *

Sherlock had never been quite so aware of the emptiness of the space around him before, the unforgivingly blank quality to the silence that greets him when he makes an observation, or a deduction. Knowing that John is there and that Sherlock can't see him is a constant nagging irritant.

After a month of frustration he buys himself a skull and places it on his mantelpiece where sits as a grinning reminder of the presence that eludes him. It doesn't help.

It must theoretically be possible, Sherlock thinks, to recreate an event in the brain like the one that had caused Molly to start to seeing Deaths. He does some digging and manages to find Molly's old MRIs – those after her epileptic incident show increased electric activity in the right parahippocampal gyrus. Any method of causing the same aberration in his own brain that Sherlock can research seems worryingly imprecise however – he does not wish to damage his intellect, certainly not without any assurance that it would actually work.

The problem seems impossible to solve, and Sherlock returns to taking cases again simply to distract himself from it. As it turns out this was the best possible thing he could have done.

* * *

The case is an intriguing one. Three siblings by the name of Tregennis living in an old house in Hampstead had apparently been sitting playing cards late into the night. The cleaning woman came round the next day to find the sister sitting stone dead in her chair and the two brothers gibbering wrecks. Lestrade texts Sherlock immediately and he arrives before the ambulance to find two brothers frothing at the mouth and writhing in their chairs.

"They've gone completely doo-lally," Donovan remarks to him as he enters. "Can't get a word of sense out of either of them."

Sherlock nods and, ignoring the corpse and the afflicted brothers, begins a survey of the room. No signs of a break in, very little out of the ordinary at all, except – Sherlock bends down to take a closer look – there is a peculiar fine residue in the fireplace.

"Your grey man is getting closer," a voice says from behind him.

Sherlock spins around.

"What?"

One of the brothers has got to his feet and is shuffling toward him, staring at him with a demented grin. "Your little grey man! Every time you look at _that_ he gets a step closer." The man's eyes bulge as he points at the fireplace. "Like grandmother's footsteps, innit? Step, step, step…Arrrgh!" The man lets out a shriek so blood curdling that Donovan starts and turns around to glare at them both.

Sherlock looks back down at the fireplace, and then at the space behind him. "Interesting," he says. Carefully he sweeps a sample of the powder into a bag and pockets it.

A little research makes the cause of the Tregennis family's distress apparent: _radix pedis diabolis_ a rare and dangerous compound made from a plant derived from the Amazon rainforest – apparently Brenda Tregennis' boyfriend was a naturalist who has brought the substance back for research purposes, and it had been stolen and used to devastating effect by a fourth, more murderously inclined sibling. Having solved the case, Sherlock leaves it to Lestrade to make the appropriate arrests, but fails to mention the small bag of evidence still sitting in his trouser pocket.

A trip to the anthropology section of the British Library and Sherlock is furnished with a rather intriguing set of insights into the terrifying drug. Apparently it was historically used in Amazonian tribes as a rite of passage for those who wished to become Shaman. One in three of those who consumed the drug died as a result of it. Many of those who survived lost their wits as a result. Of those who survived with mind intact, however, it was said that their eyes were opened to a world beyond imagining.

Sherlock turns the bag over in his fingers and thinks: _it's a chance worth taking._

Sherlock sets his experiment up carefully. He arranges himself near an open window in his flat, places the powder on a small plate with matches beside it. Then he takes his phone and composes a text to his brother.

_Conducting potentially lethal experiment (radix pedis diabolis). Tell your lackeys to wipe their feet before they enter, the carpet is new. SH._

Sherlock strikes the match and sends the text at the same instant. The powder fizzes slightly under the flame, emitting a thin wisp of smoke. Sherlock leans forward impatiently, inhaling, but nothing happens. He stirs the powder and strikes a second match. This time the powder ignites with a crackle, yellowish flame creeping across the plate. Sherlock breathes in….

And _screams_. The terror is instantaneous and wrenching. Every shadow in the room seems to have leapt to life and to be leering at him with a menace Sherlock has never encountered in the most determined of killers. His heart clenches painfully in his chest, and Sherlock finds himself desperately trying to draw in a breath but smoke is rising from the powder in thick choking billows. He scrabbles for the window attempting to open it further, when a face swims out of the eddying smoke, pale grey and hardened with anger.

"_What have you done?_"

Sherlock takes a deep gasp of the freezing night air and finds himself falling backwards into the dark.


	2. Chapter 2

Sherlock wakes to the unmistakeable smell and texture of hospital sheets. There is a bleeping that Sherlock assumes is a heart monitor, and beneath that the quieter sound of someone breathing. Sherlock opens one eye, an exercise that confirms his suspicion that any exposure to light is likely to exacerbate the blinding headache radiating up from the base of his skull. He forgets about the headache however when he takes in the contents of the room – bed, heart monitor, CCTV camera (Mycroft: dull) and, in the corner of the room, a chair, in which a grey man is sitting with his head in his hands. Sherlock struggles to a sitting position, staring.

"It worked," he says.

John looks up at him and for a moment they simply stare at each other. Sherlock marvels at the way the light falls on the supple grey texture of his skin, and catches in his hair, the dark gleam of his eyes.

"Are you _serious_?" John says. He springs to his feet, small body taut with tension. He paces a few steps across the room and then back again, before stopping to glare at Sherlock.

"You know that no one else does this, right? No one I know of, no one _anywhere_ puts their Death through the crap you put me through. I mean look at me!"John gestures to his face. "I'm thirty years old and I look fucking fifty because of the stress you put me through. Fucking – drugs and experiments and psychics, Sherlock and now this? _Devil's foot_, do you even know what it could have done to you? And you just inhaled it like it was fucking – candy floss."

"You don't inhale candy floss," Sherlock points out.

"You – what?"

"You don't inhale candy floss. That's a terrible metaphor. You eat it."

John stares at him for several beats, mouth sagging open, eyes looking glazed.

"Oh," John says, eventually. "Oh, god. You really can see me, can't you?"

"Of course. I thought that had been established."

John's knees seem abruptly to give way, and he slumps back against the wall and then staggers over to his chair to sit. "Shit," he says. "Shit, shit, shit."

"It's funny," Sherlock says. "Molly told me Deaths were quiet. Do you often shout at me like that?"

John looks up at him. "All the time," he says, faintly.

"Seems like rather a waste of energy," Sherlock comments. "If I can't hear you, what is the point in berating me?"

"I guess… I always hoped it'd filter through somehow." John says, slowly. "You can really see me? Properly see me? And… hear me?"

"Obviously."

"Bloody hell," says John, in a tone that is now a little awed. "You actually bloody did it."

Sherlock preens a little.

"That's not a compliment," John snaps. "This isn't supposed to happen."

Sherlock scowls. "I don't see why not."

"Because," John says. "This isn't the way things are supposed to be."

Sherlock rolls his eyes. "Dull."

John sighs, "You know," he says. "When I was little my Mum told me I'd have a difficult time with you. You're a loose thread."

"A loose thread?" Sherlock repeats.

"Yeah, you know. Fate is like a tapestry. Things are – not set in stone exactly but stitched in. The pattern can change sometimes, can be unpicked if someone makes an unexpected decision – but mostly, they stay the same. That's why most Deaths know how close their human is. They know where to stand, they when to be ready. But you – it's like fate didn't know what to do with you, so it just left you dangling. Your destiny is…" John shrugs. "I used to think maybe it was because you were going to die young. Now maybe I think it was because of - this. Because this is the kind of thing you do. You're the kind of mad bastard who'll go and unpick the fabric of the Universe because you have to know how everything works."

"This upsets you?"

"Of course it does," says John. "Destiny is my job."

"Then why are you smiling?"

It's true. The corners of John's mouth have been curling upwards for a while.

John reaches up a hand to cover his mouth, but the drops it when it's clear the smile isn't fading. He shakes his head. "Oh, it's just – only you would do this, Sherlock."

"So you said," Sherlock says. "Apparently I'm so impossible I've prematurely aged you." He can't keep the slight edge of hurt out of his tone at this.

John gives him a searching, thoughtful look. "Yeah, well," he says. "There is that. But I'm never bored."

"I should hope not," Sherlock says.

John looks at him, a fond smile spreading slowly across his face, the sort of smile that somehow manages to defeat Sherlock's attempt at wounded dignity, and he finds himself grinning back.

"So, you can see me," John says, leaning back in his chair and stretching his legs out in front of him. "This should be interesting."

* * *

Mycroft arrives the next morning, face pale and pinched, hand clenched on the handle of his umbrella. Mycroft hates hospitals, which begs the question of why he is here now. Sherlock can only assume it is supposed to be some sort of declaration of power and strength before which Sherlock is supposed to cower and tremble.

"Well, Sherlock," Mycroft says. "You really have outdone yourself this time."

"It was a necessary experiment."

"Your heart stopped for over a minute. Paramedics had difficulty restarting it. I suggest you think twice before attempting any similar scientific endeavours in the near future."

Sherlock leans back in his bed and glares at him. John, who is standing pressed against the back wall, gave him a sharp look.

"He's trying to protect you."

Mycroft follows Sherlock's gaze to look at the corner and then turns back to look at Sherlock, frowning.

"Devil's foot is known to have ongoing effects. Hallucinations. Bouts of extreme terror. You wouldn't happen to be experiencing any of that, would you?"

"Of course not," Sherlock says.

"The nurses mentioned you'd been talking to yourself."

"It's customary to address yourself to the most intelligent person in the room - didn't you tell me that once?"

John snorts. Sherlock, very carefully, does not look in his direction.

"J.R.R. Tolkien," Mycroft mutters, then fixes Sherlock with a stern look. "I regret to inform you that you are out of home. Your landlord was most insistent – you are to leave by the end of the week."

"I told you to be careful of the carpet."

"I believe it was your willingness to gas yourself and potentially everyone else in the building that was the sticking point, rather than the carpet. This is your third eviction this year."

"I'll find something."

"You better had. Otherwise – you know my doors are always open to you, brother."

"I'd rather take my chances under a bridge," Sherlock retorts.

"Yes," Mycroft says. "I know you would. I hope for Mummy's sake you won't let it come to that, however. I haven't told them about your current escapade. I hope you will not render it necessary for me to do so."

"Is that a threat?"

Mycroft looks at him, and Sherlock sees bags under his eyes, a weariness in his eyes that's unfamiliar. "It is a statement of fact, Sherlock. Don't tie my hands."

Mycroft moves to the door and pauses for a moment, looking at the corner where John is standing for a long moment then glances back at Sherlock, who struggles not to tense.

"If you find yourself in need of additional medical care please do not hesitate to inform me."

"I won't."

Mycroft nods shortly, then leaves.

John sighs and steps forward.

"He's got a point, you know."

"Does he?"

"We don't know exactly what that drug did to you. Obviously, you can see me now. Can you see anything else from the second realm?"

"The second…"

John waves a hand impatiently. "The stuff when we can see and you can't. Do you see anything unusual apart from me?"

"No."

"Nothing in the corner of that room, for example?" John points.

Sherlock turns to look at the empty corner and shakes his head.

"When your brother came into the room, you didn't see a woman with him? Short, fair haired, looks a bit like me?"

"No. The woman is Mycroft's Death?"

"Yeah. My sister, Harry. You'd like her. She can't stand Mycroft either."

"How do familial relationships between Deaths come about? You mentioned your mother earlier too."

"Same way they do for you. My mum is your mum's Death. My dad is your dad's and when they get together…"

John leaves an expressive pause.

"I see. But surely that necessitates forming romantic bonds only in parallel with humans."

"I guess it does, but I've never known anyone who thought it was a hardship. We feel what you feel a lot of the time," John smiles. "Not like I've ever had to worry about that with you, anyway."

"Certainly not. So. You feel my emotions."

"Some of them," John repeats. "I don't get nearly as bored as you do, thank God. Nor do I get quite as annoyed by your brother." John glances at him. "Have you noticed – when he's here I can't stand so close to you?"

"Meaning?"

"Meaning death isn't as close to you when he's around. Like I said. He's a pain, but he's your big brother. He's protecting you."

Sherlock glares at him. "Are you sure it isn't just that life _feels_ longer when he's here bothering me?"

John laughs and goes over to the table where Sherlock's gifts from well wishers sit. He picks up a grape and puts it in his mouth. "Maybe," he says. "Still." He raises his eyebrows at Sherlock "So, we need a place to stay."

"Yes," says Sherlock, thoughtfully. He likes the sound of the _we_ in that sentence rather a lot. "Yes, we do."

* * *

In the end Sherlock is able to call in a favour from an old client – Mrs Hudson, whose enduring gratitude to Sherlock for relieving her of her late husband has taken the form of various baked goods over the years and now materialises again in the form of subsidised rent on a flat in Baker Street.

Sherlock likes the flat immediately – it's a little large for one man but he has no desire to take a flatmate – that would make communicating with John most difficult. He watches as John wanders around it, poking his nose in cabinets and shifting through the boxes Mycroft has had moved here.

"We'll need to clear up a bit," John says.

"You can if you like," Sherlock pushes a box off the sofa and lounges on it. John shoots him a nasty look.

"And what are you doing?"

"Thinking."

"About?"

Sherlock pauses and listens to the sound of a familiar car pulling up outside Baker Street. He smiles at John. "There's been another murder."

* * *

Living with a visible, audible John proves invaluable in many respects, not least of which is John's help at crime scenes. John has few deductive skills (disappointingly – Sherlock would have thought a lifetime of following him around would have taught John _something_) but Sherlock finds his wits can be sharpened against the whetstone of John's quiet interest. And John's awareness of a world Sherlock cannot see proves most useful at times, not to mention his proximity makes a useful barometer for Sherlock to gauge just how dangerous the people around him might be.

"Are you an idiot?" John asks him, on the first night they are on a case together, the delightful mystery of a suicide-inducing taxi driver. "_Both _those pills are poisonous. Have you not noticed I'm breathing down your neck whenever you touch either one of them?"

Sherlock Holmes looks up into the mocking eyes of the taxi driver. "You're cheating," he says. "No dice. And the police will be here – oh, about now. Good luck managing your terminal illness in prison."

After the case ends Sherlock and John return to the flat, still in fits of laughter over the cabbie's flummoxed expression.

It isn't only cases that are improved by John's presence however. Sherlock, who has never been good at living at close quarters with anyone, is amazed by how much he enjoys looking up to see John pottering around on the other side of the flat, making tea in the kitchen, or flicking through a newspaper. There's an ease of familiarity to their interaction which Sherlock supposes could be explained by the years they lived side by side but silently, but also an underlying sparkle of excitement like frost in the air, sharpening Sherlock's senses and making even mundane activities seem almost exciting. Genius needs an audience, he tells himself, and John is perfect for the job.

Their days settle into a sort of pattern around one another. Most days John is, sometimes frustratingly, physically distant from Sherlock, keeping the length of the flat between them. Sherlock knows John likes the distant days, because he smiles over thirty per cent more frequently and hums to himself as he makes his tea. Privately Sherlock would be prepared to suffer a bit more mortal peril to avoid having to squint to read John's expression or to conduct all his conversations by shouting across the length of the flat but he does not share that thought with John.

Then there are times when John seems pulled closer and closer, into Sherlock's orbit. Sometimes the reasons are obvious –Sherlock is conducting experiments on a series of poisonous chemicals, Sherlock is hunting down a serial killer, Sherlock's untended cold is building into pneumonia. Sometimes Sherlock wakes up to find John, for no reason he can discern, sitting at the foot of his bed, tight lipped and tense. It's clear John hates the days they spend within arm's reach of one another – he clams up, avoiding Sherlock's eyes, turning his head away whenever Sherlock speaks.

"It isn't my fault," Sherlock points out once, to which John only glares at him.

"You could be more careful," John snaps, and turns pointedly away from him.

Occasionally are days that are a perfect medium, where John is close enough to smile at, sitting in the chair opposite his own, days when John will smile back, the warmth that had made such an impression on Sherlock on that first day under the tree kindling in his eyes.

* * *

The issue of space comes to a head unexpectedly six months after they move into Baker Street. It's been a close-quarters sort of day, to John's obvious but unspoken irritation. Sherlock has been awake for two days on a case which has now finally concluded and feels his head growing heavy and stupid with the desire to sleep. John trails after him into his bedroom and wheels out the campbed from under Sherlock's bed. Despite being a supernatural being John needs to sleep, as it turns out, as much if not more than Sherlock does. The nature of the always shifting distance between them means John's bed must be as mobile as he is. Today, the campbed is pulled to the foot of Sherlock's bed, and Sherlock sits up against the pillows, watching John settle under the blankets.

Despite Sherlock's exhaustion, sleep doesn't come easily for him. Instead Sherlock listens as John's breathing slows and deepens, a bar of light from the corridor beyond illuminating his face. Sherlock finds himself watching the tiny shifts in expression as John moves through his REM cycle, the flutter of his lashes on his cheeks. His face is never so relaxed during the waking day and Sherlock rarely has a chance to observe him so closely.

Since he isn't sleeping Sherlock decides there will be little harm in moving a little closer to John to look. He stands and walks over to John's bed, looking down at him, watching his own shadow pass over John's face.

That's when John opens his eyes and smiles. He reaches a hand up to Sherlock to catch at his wrist, winding his fingers around it. Sherlock feels a shock at the sensation of his own pulse jumping under John's fingers. Something in his brain telling him this is wrong, that it is not supposed to happen, but his knees bend despite themselves, and he sits on the edge of John's bed. John's eyes gleam in the darkness as he takes Sherlock's hand again and raises it to his mouth, brushing his lips over Sherlock's fingers before turning his hand over, to kiss the flat of his palm.

"John," Sherlock says hoarsely, but John raises a finger to his lips, and then kneels up so their faces are level. One hand travels down the side of Sherlock's face and rakes through his hair before John moves forward and presses their lips together, his mouth warm and sweet and moving under Sherlock's. That's when something in Sherlock seems to give, a heated wanting flooding through him and Sherlock finds himself pushing back greedily, laying John flat on the bed and scrambling on top of him, hands plucking and pulling at his pyjamas. John responds by wrapping his legs around Sherlock, pulling him in until everything is lost to the sound of their shared laboured breaths and the tug of friction between them. Eventually John arches up beneath him and cries out his name, quiet and clear and in that moment Sherlock finds himself coming with a cry of relief.

And then he opens his eyes. He's in his own bed, sheets tangled and damp around him. John is still in his camp bed at the foot of his bed, but he's sitting bolt upright now and staring at Sherlock.

"John," Sherlock says. "I was… I was dreaming…."

"Yes," John says, in clipped tones. "I know."

Sherlock takes a few minutes of breathing to gather in the meaning of the situation, and then his cheeks start to burn.

"I take it we share dreams then too."

"Sometimes," John says. He struggles to his feet and walks with awkward halting steps that Sherlock can tell aren't voluntary over to Sherlock's bed to sit beside Sherlock's knees. The expression on John's face as he looks down at him is very cold. Sherlock feels as if he's swallowed something sharp cornered and cruel and that it has lodged itself somewhere in his gullet.

There is a silence. Sherlock wishes he could see John's face but he's turned his face away, casting it into shadow.

"I suppose it's only natural," John says, at last. "You were very young when you saw me first. That isn't supposed to happen. And when you die, chemicals are released – endorphins, dopamine, causing sensations not unlike how you'd feel when you…. I can see how things could have become confused."

"I'm not confused," says Sherlock, as he says it he knows it's true. Ever since he's seen John there's been a desire like a hook somewhere deep in his chest and even making him visible isn't enough. "I've never wanted anyone John. But I want you."

Something flashes over the still surface of John's face, almost too quickly for Sherlock to interpret but when he does he feels a little warmer.

"And you want me," Sherlock says. "It was your dream as much as mine, wasn't it? You kissed me first."

John is silent for a long moment. Eventually he turns, eyes gleaming in the dark. "Perhaps," he says slowly. "I'm confused too."

Sherlock struggles into a sitting position and John automatically leans back and away from him. Sherlock stares at him, at the ruffled grey hair, at the puffy sleep-bright eyes, the chest rising and falling under his open pyjama shirt. His hands twitch in his lap with the stifled desire to touch.

"I found a way to make you visible…."

"No," John says.

"But…."

John gets to his feet, and gives a hobbled half step before stopping, clearly unable to get any further away from Sherlock. With a short grunt of frustration he turns and walks over to Sherlock's bed table and, picking up his glass of water and throwing it against a wall. They both stare at the shattered pieces.

"I'm sorry." John says, raising a hand to cover his face. "It's just - listen to me. If a Death touches a human, that human _dies_. That's the rule."

"Ah yes, your fondness for _the rules_," Sherlock sneers. A muscle twitches at the corner of John's jaw, his face hardening

"I am fond of obeying rules that keep you from dying, Sherlock, yeah. And you know what? If you even think about trying to break this one, about running any more of your experiments, on _us_ I'll…"

"What?" says Sherlock. "What can you do, other than shouting me, at which you are performing admirably at already, by the way."

John clenches his fists and leans forward, fury-dilated eyes boring into Sherlock's

"I'll walk away from you, Sherlock. I'll get up and leave. Whether you are alive or dead, I'll make sure you won't see me again."

There's a silence in which Sherlock absorbs the sheer fury in John's expression.

"I thought Deaths couldn't do that," he says.

"Oh, we can. It would be incredibly painful for both of us. It would probably be easier for me to lop off a limb, or scoop out one of my internal organs and hand it to you. But I will do it, Sherlock, if you do _anything_ to experiment on us again."

Sherlock stares at him for a long moment, at his pale taut face and then nods.

"Understood."

John lets out a breath and gets up, stepping away from him and sitting at the far end of Sherlock's bed.

"You have to know, Sherlock, it's…" John begins, and looks away. "I know you are who you are. I know dying doesn't scare you. But it scares me. The thought of being the one to take you away from this world, from your work... You don't see the good you do with that ridiculous brain of yours, the impact you have on the world around you. On the second realm, as well as this one. But I can. And to for you throw that away - "

John's breath hitches for a moment and he looks away. "Both me and Harry, we were always so proud of you and Mycroft. No one else had humans like you."

"Stressful and detestable."

"And brilliant and exciting and mad." John smiles at him. "We used to fight over whose human was better."

Sherlock raises his eyebrows. "I hope you're going to tell me that you were the victor."

"Well," John says. "I certainly like to think so."

They smile at one another, and Sherlock enjoys returning warmth in John's gaze. Perhaps, he thinks, it will be enough, the quiet presence of John beside him and sleep-warm conversations after the lights have been turned out. Then John yawns and ruffles his soft looking hair and Sherlock thinks _you will never touch him, not until the day you die._

"I suppose we should try to sleep," John says. Sherlock nods, awkwardly and looks away.

"Before we do…" John says, he leans forward just slightly, spreading his hands open on the coverlet in front of him. "Like I said, I know our life will always be dangerous, but I'd like you to – take some more care. For me, if not for yourself."

Sherlock looks at him for a long moment, and then nods. "I will endeavour to avoid dying," he says. "To the best of my ability."

"Good," John says. "Thank you."

With a last smile John gets up and returns to bed. Sherlock stares at the line of his Death's body under the blankets for a long time before he finds himself able to lie down again and sleep.

* * *

It's three months after John makes his ultimatum and Sherlock makes his promise when Sherlock gets a text message from an unknown number.

_Hi Sherlock, it's Molly Hooper. I've come across something rather odd and I wasn't sure who else to ask about it and, well, I remembered you were a detective. Any chance you could stop by Barts?_

As it happens, Sherlock has some samples from his most recent case that would benefit from examination under the superior lab equipment at St. Barts, so Sherlock decides to kill two birds with one stone and take them with him. Molly meets them in the lab, looking pale and harassed.

"Thank you for coming," Molly says.

"Not a problem," Sherlock says. "Where is the crime?"

"Crime?"

"I assume that's why you asked me here."

"Oh! No – not exactly. It's just there's… someone I'd like you to take a look at. I'd like to know what you think of him. I can't… I'm not sure if anything's wrong at all, but it might be. He should be arriving in half an hour or so, if you'll just…"

Sherlock raises his eyebrows at this uncharacteristically vague pronouncement but he can see it would be fruitless to pursue the matter.

"Would you mind if I take a look at these samples in the meantime?"

"Of course…"

Molly sits on the lab stool beside him and pulls out a report, and Sherlock begins unpacking his samples.

"Sherlock," John says in warning tones, as he takes a step closer to him. "Gloves."

Sherlock glances down at the corrosive substance he'd been handling and sighs, going over to the glove dispenser.

Molly watches them both with an expression of dawning surprise on her face. "You can hear him now?"

"And see him. Devil's Foot," says Sherlock, winks at her. "Psychoactive compound. It was all rather thrilling."

"Oh, wow, well," she says, still sounding a bit nonplussed. "I'm glad it - worked out?"

John makes a cynical noise in the back of his throat at that, but Sherlock only smiles at him widely.

It's at this moment that the door bangs open, and a young man sticks his head around it. "Molly.. oh, sorry I didn't realise you had company. I brought that tech manual you asked for."

"Oh, it's quite all right, Jim, come in." Molly says, in rather too high pitched a tone. Sherlock raises his eyebrows at her. Clearly this is the person Molly was hoping Sherlock would examine.

Sherlock scans him quickly. There is nothing exceptional about him that Sherlock can see – he clearly works in IT, has a mild addiction to pain medication, probably the result of a chronic condition, is gay and, judging by the shuffle of nervous enthusiasm he greets Sherlock with, single. Overall intensely unthreatening and more than usually dull.

Then Sherlock glances sideways and notices that beside him John has gone rigid, staring at the man in a kind of mute horror.

"…heard so much about you," Jim finishes saying, hand held out to Sherlock. Sherlock merely stares at him, and Molly gives a nervous giggle.

"Oh, Sherlock has been touching all sorts of nasty substances, you don't want to…."

"Oh, no of course not, excuse me. I'll get out of your hair." Jim says, dropping the hand and backs away, knocking over a petri dish as he goes. Sherlock catches the flash of a card sliding under the dish as Jim puts it back.

"Well. Be seeing you, Molly,"

"Oh – yes." Molly says, still looking flustered and sees him to the door. The three of them wait in silence until the door has snapped shut decisively behind Jim.

"Well?" Molly looks questioningly at Sherlock, but Sherlock is too busy looking at John, who is hunched forward taking deep shuddering breaths, as if afraid he might throw up.

"What's wrong?" Sherlock asks, and John looks up at him, a distinctly queasy expression on his face.

"He doesn't have a Death," he says.

Sherlock looks back at the closed door. "That man? Jim?"

John nods, and shivers.

"That's… unusual?"

"It's- you wouldn't understand. It's like seeing someone without a head." John blinks and then seems to remember who he is talking to. "It's like how a _normal_ human would feel seeing someone without a head."

"Toby was the same," Molly says. "The first time we met him I thought Toby was going to faint. You didn't notice anything off about him, then?"

Sherlock shakes his head slowly. "Nothing that seemed of any significance," he says. "Certainly no signs of criminal intent if that is what you are asking about."

Molly sighs, and perches on a lab stool. "He's been really nice to me these past couple of months, made a real effort to be friends. He's always asking after me, bringing me coffees, presents for my cat. I've no reason to think there's anything wrong other than… other than that."

John shakes his head jerkily. "Don't trust him. Stay away."

"That's what Toby says. But what can I say? No, he can't buy me coffee or chat about the latest episode of Glee because he doesn't have a supernatural being that only I can see following him around?"

"Why would a person not have a Death?" Sherlock asks. "Could he have been born without one?"

"He'd be immortal," says John. "Ever heard of that happening?"

"Perhaps his Death left him," Sherlock says. John glances up at him, and then away.

"Maybe. That's – rare," he says. "Molly, I don't know what we can tell you except be really careful around him."

"We could investigate him," Sherlock points out. John glares at him.

"You're a detective," he says. "Not a paranormal investigator. No one has committed any crimes here."

"As far as we know," Sherlock mutters.

"Isn't there anyone else you could ask for advice, Molly?"

Molly bites her lip. "Well, that's just it. I tried to contact my old necromancy teacher…."

Sherlock's head snaps up. "You were taught necromancy?"

"Yes – well, sort of. As I said, when I first started seeing things I was terrified out of my mind. Then I met Alfredo and he could see some of the same things, and he – well, he knew stuff. He'd travelled all the way around the world when he was young, learning what he could about the Second Realm. He helped explain a lot of things to me, helped me adjust. When I have questions I usually ask him. But he hasn't been picking up his calls recently, and there's no answer at his flat."

Sherlock sits up at this. "Seems like rather a coincidence."

"Well, not really. Alfredo travels a lot. Last year he disappeared for six months – turned out he'd got the urge to go hiking over the Andes and didn't think to let anyone know about it."

"Hmm," Sherlock looks up at John. "Nevertheless. Perhaps John and I can look into tracing Alfredo, just as a precautionary measure. I have plenty of contacts in backpacking communities."

John frowns, but eventually nods. "I suppose there's no harm in that."

Molly looks relieved. "I'll get you his address."

* * *

Alfredo D'Onofrio is dead. Sherlock is quite certain of the fact. After a week of discreet enquiries and careful digging no trace of him can be found. People _don't_ disappear so completely that Sherlock can't find a trace, not unless someone has put a great deal of thought into it. It's not just Alfredo either. Several members of Alfredo's network of past travelling companions seem to have mysteriously succumbed to the same vanishing force, all about two months ago which, coincidentally, is the same period of time since 'Jim Zucco' began working as an IT consultant at Barts.

Sherlock takes the business card with Jim's name and number on it out of his pocket, tracing the edges, and glances over at John. He's sitting on the sofa, nodding off over the print out of Alfredo's bank records that Sherlock had asked him to read. John would not approve of approaching Jim directly. But the case is at a dead end, and what other move is left for Sherlock to make?

He pulls out his phone and composes his text.

_You seem to have left a business card under my petri _

The answer is almost immediate.  
_  
Yes, I was hoping you might call :)_

_I prefer to text. SH_

_It's a shame, with a voice like yours a call would get anyone's attention._

_It doesn't seem like your attention is difficult to acquire. SH_

_Not for you, honey, no._

Sherlock looks at the word on the screen and suddenly feels a sense of utter certainty that the man he's talking to is much cleverer and much more dangerous than he'd realised.  
_  
Where is Alfredo D'Onofrio? SH_

_Oh, Sherlock, that's quite the story. Why don't you invite me to tea tomorrow afternoon and I'll tell you all about it?_

* * *

John fidgets with the tea towel in the kitchen, watching with wide eyes as Sherlock sets out the tea and biscuits in their coffee table.

"You could always go into my bedroom if you don't want to see him." Sherlock says.

"I couldn't," says John flatly and Sherlock glances up at him. If they position themselves strategically the distance between them is quite far enough for John to reach the other room.

"It's not that," John says. "I don't want to leave you alone with him."

Sherlock opens his mouth unsure how to reply to that, when the doorbell rings. He goes to the window to see Jim grin up at him briefly at him from the street before Mrs Hudson opens the door.

The Jim that enters Sherlock's living room is a different person from the shuffling IT consultant from the hospital. It's only seeing him in his Westwood suit and sharply polished shoes that makes Sherlock realise how much he'd underestimated the skill of his deception. Sherlock shows him to his seat and pours him a cup of tea.

"So," he says, settling himself into his seat.

"So," Jim mimicks his tone, and then picks up his tea cup, inhaling. "Oh, that's a lovely cuppa, I can just tell. So many people think you can just shake a tea bag over water and it will make a proper brew. It's nice to see someone do things the traditional way." He takes a sip and makes an appreciative noise. "Oh, yes, that's just right."

"Alfredo D'Onofrio," Sherlock reminds him.

"Hmmm? Oh, he's dead, Sherlock. You knew that."

"You murdered him."

"Murder-? Oh, no. I'd never get my hands dirty with something like that. The silly man went rock climbing in the Alps and, well, it seems someone somewhere along the line didn't sell him quite the right sort of rope. They'll find him eventually, I expect, at the bottom of some nice rocky gorge."

Jim sighs and takes another slurp of tea, and a bite of one of Mrs Hudson's shortbread biscuits. He looks up at John, who is watching them both from behind the kitchen counter, eyes narrowed.

"It's a shame you aren't having tea, Johnny boy, this is quite delicious."

John ignores him, looking at Sherlock. "Ask him about the others."

"Oh, I'm getting the silent treatment, am I? Yes, Sherlock, tell your Death to tell you to tell me exactly how much he hates the sight of me."

"Why have you been killing necromancers?"

"Well - you know what they say about magicians, Sherlock. It never does to reveal your tricks. And no one keeps secrets better than dead men." Jim leans forward. "As it stands I have quite the monopoly on knowledge about those particular arts right now. No one alive understands the Second Realm better than I do. Besides. I didn't want little Molly Hooper to have anyone else to turn to when she started to get worried."

"And yet you've not harmed Molly. What significance does she have to you?"

"No significance at all, except I knew that she'd introduce me to you. I've been watching you for a very long time, Sherlock."

"Have you? I'm flattered."

"Yes, we've been playing one another for a while now, not that you've noticed. You remember Jefferson Hope? He was one of mine."

"You were the sponsor."

"Amongst other things, yes. And then there was the case of the Jade Pin, well, I let you have that one. Those smugglers were too stupid not to let go. I've had my hand in so many of your little puzzles these past few years Sherlock. I'm a little disappointed that you didn't notice my input but I suppose you've been…" Jim glances up at John. "Preoccupied."

"What are you?" says Sherlock, leaning forward.

"Jim Moriarty, consulting criminal," Jim smiles at him and gives him a mocking little wave. "Hi."

Sherlock stares at the man opposite, with a growing half-revolted fascination.

"What do you want with Sherlock?" says John. He's moved a little closer now, and is standing in the entrance to his kitchen, arms folded and glaring at Moriarty. "You said all of this is to get to him, so. What is it you want?"

Moriarty's smile shows teeth. "Oh, he's very direct, isn't he? Very courageous. I can see why you like him, Sherlock, really, I do. Well, to answer your question, I like to think of myself as a Good Samaritan. You're in a terrible mess, Sherlock, and you simply can't see it."

"Am I?"

"Well, yes," Moriarty gives a pointed glance at John. "Sherlock, I understand a Death makes a very nice little pet. I was fond enough of my Sebastian, until I realised how much he was holding me back," Moriarty leans forward, face suddenly serious. "But he was. It's all very well for ordinary people to get old and sick and die, we aren't ordinary Sherlock. You are brilliant – almost as brilliant as I am. You would do so much better without that millstone around your neck. He'll chip away at you, at your abilities, at your strength. It's happening already. You would have noticed me so much sooner if he hadn't been fogging your brain."

"So, you want me to get rid of John." Sherlock states.

"I like the game we've been playing, Sherlock. I arrange crimes and you solve them, I start a waltz and you step in and change the steps. I can tell you honestly, it's the most fun I've had in years. But in a few short decades you'll start to get decrepit and gooey minded and then you'll die. Why would you want that, when we could be playmates forever?"

"You sent your own Death away," Sherlock says.

"It's actually very easy," Moriarty says. "Two words, and he's banished. Would you like me to tell you what they are?"

John makes a soft sound, from the kitchen. He's staring at them both with a look of horror Sherlock glances at him and then at Moriarty.

"I understand separating from your Death is rather a painful endeavour."

Moriarty shrugs. "What's a little pain, when you have eternity to gain for yourself? Infinite youth, infinite pleasure. The pain just sharpens the sensation."

He's lying, Sherlock thinks. Underneath that well tailored suit, every muscle of James Moriarty's body is straining, veins standing out on his neck and at his temple with the effort of holding himself still, with not screaming.

Sherlock leans forward, looking Moriarty straight in the eyes. "I have no interest in separating myself from John." he says.

Moriarty's eyes flash, lip curling up for a second. Then he forces a sickly smile.

"I had a feeling that might be your answer. I'm afraid I'll simply have to persuade you." Abruptly, Moriarty stands. "But that can wait. I'm afraid I have other business to attend to."

"Please don't hurry back."

Moriarty bares gives Sherlock a bare-toothed grin and then turns to walk toward the kitchen, stopping short in front of John, who stares back at him defiantly.

"You think you have him perfectly under your thumb, don't you? It won't last, you know. He's much too good for you."

"Get out," John says.

"Oh, I will," Moriarty say. "Ta for now, you two."

He leaves the room and John lets out a long breath.

"Are you all right?" Sherlock asks him. John nods. Sherlock goes to the window to watch Moriarty getting into a black car. He feels John come over to stand behind his shoulder.

"Well, he's not going to leave you alone. What are we going to do?"

Sherlock watches as the car slides away. "I don't know."

* * *

Moriarty's net closes in quickly. It starts with small things. Sherlock's mother calls him in distress to tell him there has been a fire in his family home – all her books and papers have been destroyed along with his father's pianoforte. A card arrives with a dozen red roses for Sherlock the next day '_Lucky no one was in the house this time, wasn't it? – M x_'. Mrs Hudson suffers an unexpected fall after a patch of ice appears mysteriously right outside their door, and the doctors hum and hah about whether she should perhaps move into a care home. Lestrade calls Sherlock to tell him he can't take him on cases anymore ('Just for a bit Sherlock, my bosses are putting me under a lot of pressure about you… to be honest I think there have been some rumours going around…'). Cases from the website dry up.

It's a power play, Sherlock realises. Moriarty is letting him know that he can systematically strip Sherlock of everything that makes his life bearable, and Sherlock has no doubt that this is only the beginning. He glances at John where he is sitting hunched in his chair by the fireplace, staring at Sherlock's laptop. There are no prizes for guessing where Moriarty will strike last.

Moriarty clearly plans to leave Sherlock with two choices, and if not for his promise to John Sherlock might be very tempted to take the latter. Sherlock needs to gain an advantage somehow, but how? Moriarty has no vulnerabilities. Even the British Government can threaten little against a man who cannot die and to whom any pain one can inflict will matter little compared to the agony he has already invited upon himself.

Unless. Perhaps Moriarty is right. Perhaps buried deep in this mess is a small glimmer of opportunity.

Sherlock glances at the still preoccupied John and then takes out his mobile thumbing a text surreptitiously under the table. _Molly – come to Baker Street tonight at 12pm. I need to talk to you, and I need to do it while John is asleep._.

* * *

"What are we going to do?" John pants as together they duck into a doorway. Behind them a police siren wails and Sherlock hears the screeching of brakes kicked into gear. Sherlock's near-arrest and pending tabloid disgrace undoubtedly signals the commencement of Moriarty's end game. It's time to act.

"We need to give Moriarty what he wants," Sherlock says. He glances at John, taut, worried, watching him. "St Barts. Let's go."

Moriarty is waiting for them in the lab, sitting cross legged on the counter top.

"Well, Sherlock. Things are going well, aren't they? Have you thought anymore about my offer?"

Sherlock takes off his coat and throws it over a chair. Then he pulls the gun out of his pocket slowly and levels it at Moriarty, who pouts.

"Now, now, I thought you were smarter than that. I'm immortal. You can't kill me."

"I know," says Sherlock. "It isn't for you."

Beside him, Sherlock feels John tense. "Sherlock-"

Moriarty's face darkens. "You're really going to choose suicide? You'd prefer _that_ to spending eternity with me?"

"This is choice you've given me, isn't it?" Sherlock points out. "Either I banish my Death, or I kill myself to prevent you destroying everything that matters to me – killing my family and friends, destroying my work."

"Well, yes, but I thought you'd make the sensible decision."

Sherlock pauses, staring at Moriarty. "I still might." He opens the gun chamber and shakes the bullets out into his hand.

"You said you like playing games. Let's make this into a game." Sherlock places a single bullet back spins the chamber. He pulls over a labstool and sits in front of Moriarty. "Russian roulette. The bullet falls on my turn and I'll be dead, just as you planned. The bullet falls on yours and I'll do as you say. Banish John. We can start another life together."

"Heads I win, tails you lose," Moriarty says. "I like it. But it doesn't sound like it would much fun for you."

Sherlock shrugs. "One way or another, I've lost. May as well do it in style."

"All right," Jim picks up the gun, and polishes it lovingly for a moment. With an indulgent smile at Sherlock, he raises the gun to his head and pulls the trigger. There is a quiet click, followed by silence.

"One down," Moriarty winks as he hands the gun back to Sherlock.

"Sherlock, please," John says, stepping closer as Sherlock raises the gun to his own temple. "There must be another way to…."

Sherlock pulls the trigger. Again the same quiet click.

Moriarty takes the gun back, gives it a measuring shake.

"Oh, I think this one might be the lucky one!" he says. "You know what that means, Johnny boy."

John shifts, looking squeamish.

Moriarty raises the gun and fires. This crack of the bullet resonates in the darkened room, ringing in Sherlock's ears and temporarily deafening him. Moriarty slumps forwards, blood pouring out of his head wound… and then, hands tightening on the desk in front of him, he pulls himself back up. He pulls a handkerchief out of his breast pocket and dabs, with ridiculous delicacy, at the gushing head wound.

"Well, that was unpleasant," he says. "Still I suppose it's decided now."

"I suppose it is," Sherlock says calmly.

"The words for banishment are _Maveth Nadach_. Well, go ahead, I'm waiting."

"I will," Sherlock says. "But first," he beckons to Moriarty, who leans forward, blood dripping from his head and onto the shoulder of Sherlock's shirt. "Did it ever occur to you?" Sherlock whispers in Moriarty's half blasted ear. "That for a person to die they need a Death? There's no rule that Death has to be their own."

There's a silence as Moriarty blinks, absorbing what Sherlock has said, and then Sherlock stands over the desk, pulling Moriarty up onto his feet by the lapels of his suit.

"Sherlock, what-" John says, and gasps as Sherlock bodily shoves Moriarty towards John, both of them colliding and falling to the floor. Moriarty's body goes instantly limp, eyes open and staring. Sherlock steps to one side, to look at them both.

John blinks up at him, eyes wide with confusion.

"Sherlock-"

"Maveth Nadach," Sherlock says flatly.

John's breath hitches. "_Sherlock,_" He gasps and Sherlock turns away, unable to bear dawning look of betrayal in John's eyes.

"You didn't want me to die," Sherlock says. "Now, I won't."

He can feel the pain spreading slowly outwards from the centre of his chest, a dark shivering bleakness that only sharpen as he hears John get to his feet and walk with dragging feet to the door.

It's only once the door has slammed shut that Sherlock feels the full weight of what he has done slam into him, agony making him double over, stomach roiling. He retches twice. He can hear an odd swooping sound in his ears and when he opens his eyes he almost screams.

A huge figure has appeared in the centre of the room, a giant mothlike being with a slavering twisted face glaring down at him as it sweeps it's tattered wings through the air, advancing towards him. Sherlock does cry out then, out of sheer terror and pain, covering his eyes and curling into himself.

He's not sure how long he's on the floor, shivering and aching as the creature above him hisses and swoops above him, but eventually Sherlock becomes aware of a change in the room around him, the sound of footsteps and then the warm weight of an arm on his shoulder, a soft hand touching his cheek.

"It can't hurt you," Molly says. "It's in that realm, not this one."

Sherlock looks up. Molly is kneeling in from of him. Behind her the creature has backed off and has taken to beating it's wings against the window at the far side of the room. So this is what it is like to be able to see into the Second Realm, Sherlock thinks. He doesn't envy Molly or John their abilities at all.

"You did it then?" Molly says.

Sherlock nods. "It hurts, Molly."

"It will," Molly says. "But if you want our plan to work, you're going to have to pull yourself together. Can you stand?"

Sherlock nods and slowly gets to his feet, Molly supporting him. He becomes aware of a man, round faced and worried looking, standing by the door.

"Toby, I presume," Sherlock says, and the Death cringes away from him.

"It's all right, Toby," Molly says. "Sherlock did what he had to do. Now," she sits Sherlock down and brings him a glass of water. "You have a long journey ahead of you. Do you remember everything I said?"


	3. Chapter 3

It takes Sherlock four months to find Moriarty's Death, lurking in the bombed out ruins of a village in Afghanistan. At the sight of Sherlock he shudders and tries to slink away but Sherlock holds up his hand "Sebastian," he says.

Moriarty's Death halts, frozen in place.

"Interesting place to choose to live," Sherlock says.

"War," says Sebastian. His voice has a hoarse rusty quality, like a hinge on a decaying door. "People dying everywhere. I hoped somehow I'd find a way, in the confusion to get close to someone… that one of them would take me with them."

"But they didn't."

Sebastian hisses, showing surprisingly sharp teeth. "Their Deaths wouldn't let me get close."

"Unfortunate for you," Sherlock takes a step closer and the Death glares at him. He isn't much like John, Sherlock thinks. His skin is grey but a shade lighter than John's and where John is small, compact and soft featured, Sebastian is tall, long limbed and almost painfully angular. His eyes are dark hollows in his gaunt face.

"Did you come from Jim?" Sebastian asks.

Sherlock hesitates. He needs to gain the Death's trust but it's unclear if appearing under the guise of Moriarty's friend will help or hinder him in this endeavour. The Death's face offers no clues – his expression is sullen, eyes watchfully fixed on Sherlock's face.

"I know him," Sherlock says eventually.

Sebastian blinks a few times, then tilts his head. "How is he?"

"Not well," Sherlock says.

A shiver seems to pass over the Death's face, dark eyes glistening with tears. "He banished me," he says.

"Yes," says Sherlock. "I know."

"I loved him. How could he do that to me? How could he do that to us both?" The Death's voice breaks and Sherlock has to look away, suddenly uncomfortably reminded of John. He swallows hard and takes a breath.

"Jim made a mistake," he says. "A terrible mistake. And he regrets it, though he's too proud to admit it."

The death lets out a soft whine of misery, like a dog pining for affection. The sounds sets Sherlock's teeth on edge. He clenches his fists and continues.

"I can help you find him again," he says.

The Death's eyes narrow. "Why should I trust you?" he asks. "You've obviously done away with your own Death. You're just like him."

"On the contrary," Sherlock says. "I became separated from my Death in an – accident. In fact, he's with Jim now. I need _your_ help to reach him again." Sherlock takes a step closer to the trembling death in front of him, fixing him with his most persuasive look. "Please Sebastian. We can help each other."

Sebastian takes a deep breath, and says. "Where is Jim?"

Sherlock smiles. "The Underworld," he says.

They walk for days, Sebastian leading the way wordlessly through teeming cities and empty desert wastes, through lush forest paths grown tangled with plants Sherlock doesn't recognise, through mountain passes so sharp they see like gashes between rock and sky. Sherlock, who memorised the geography of the middle-east as a child is quickly convinced that this journey is not in any part of it charted on the map and, in fact, might be part of another world entirely, though where they crossed from Sherlock's world to this, he cannot say.

Sherlock imagines taking this journey with John, exploring these unearthly wonders together and feels a familiar tug of pain in his chest.

Eventually they reach a wide moor with a dark mountain brooding heavily on the horizon ahead of them. Sebastian pauses for a moment, looking around him, as if listening for something and then turns and walks off into the heather. Sherlock follows him. They cut a zigzagging course through the moor until they find a stream which, apparently, is what Sebastian has been looking for because he looks at Sherlock and smiles. It takes Sherlock a few moments to realise what is wrong with the water – it's flowing uphill, away from them and towards the mountain.

"Come on," Sebastian says, his voice hoarse. These are the first words he's spoken since they left Afghanistan. Sherlock swallows and tries to quell the sudden and unreasonable revulsion that rises in him at the sight of the back-flowing water, and nods. They follow the stream through the moor until they reach the foot of the mountain, which throws them into deep shadow. Here there is a small gap where the water disappears underground, rushing into the dark. Sebastian pauses and looks at Sherlock.

"Here," he says.

Sherlock looks at the narrow gap through which the water is being sucked.

"I take it there isn't another entrance."

Sebastian only raises his eyebrows and shakes his head. "Last chance to turn back," he remarks.

"I'm not going to do that," Sherlock says. He takes off his coat, carefully folding it and placing it under a boulder for safekeeping and slips off his shoes and socks. Sebastian watches his preparations with detached interest. When Sherlock nods to show him he's finished, Sebastian grins and then steps forward, walking straight into the centre of the river, where it's waist deep and then abruptly dives under the rushing waters and out of sight.

Sherlock steps in after him. The water is freezing and current is strong, swiftly pulling him off his feet and under the black smothering waters. Sherlock kicks out, trying to right himself but it's too late – he feels rock scrape against knees as he's pushed through the narrow gap and into the bowels of the mountain. The water presses close and cold, forcing itself into Sherlock's ears, nose, lungs. The cold is so intense he thinks it will stop his heart, and only his lungs seem to be burning, begging for air. Sherlock isn't sure how long he's been underwater but he's certain he can't maintain consciousness for much longer.

And then suddenly the river spits him out, and he's scrabbling at an earthen floor taking deep breaths. He can hear the rushing of water and the sound of Sebastian coughing and sputtering beside him. He pulls himself up to look around him. He's in some sort of underground cave, lit at intervals by blue flamed torches. The stream runs along a groove in the middle of the cave, gleaming in the torchlight.

"Ready?" Sebastian says, and Sherlock looks up at him and nods.

They walk through twisting stone passages carved through the rock. The path forks and they turn away from the river and on until the sound of it fades. Sherlock keeps careful track of every turn Sebastian makes – left, right, left, left – uncertain of whether he will need to find his way back.

Eventually they reach a vast stone chamber which, in contrast to the narrow passages, is brightly lit with a cheerful chandelier emitting a soft yellow light. In the centre of the chamber, incongruously, sits a desk rather like the one in Mycroft's office, all gleaming mahogany, green leather and brass. A grey haired woman sits at the desk apparently absorbed in reading through a sheaf of paper, half moon glasses resting on the bridge of her nose.

Sherlock clears his throat and the woman looks up.

"Hello," says Sherlock, crossing the floor towards her. "Allow me to introduce myself. My name is Sherlock Holmes, and this is Sebastian."

The woman glances at her watch and sighs. "You aren't expected."

"I've come to help you rectify a mistake." The woman's eyebrows rise as if she thinks this is a great impertinence. "I'm sure you're aware James Moriarty came here with the wrong Death."

"Yes, that was a mess," the woman says. "I can't tell you the paperwork that sort of thing causes."

"Quite," says Sherlock. The woman looks at him, her small head cocked inquisitively as if expecting him to go on.

"Well," says Sherlock, gesturing at Sebastian who is still lingering anxiously at the entrance. "I've brought Moriarty's own Death to you. I was hoping…"

"Yes?"

Sherlock clears his throat. "I've done you a favour. I can't imagine you like having people without Deaths running around, people pairing themselves with the wrong deaths."

The woman smiles fondly and Sherlock is uncomfortably reminded of his mother.

"What makes you think I mind?"

Sherlock shrugs. "I presume Death is like anywhere else. At the end of the day, the books have to balance."

"Hmmm," the woman's smile broadens, revealing dimples. "You are a clever boy. I've heard such a lot about you."

"Oh?"

"From recently deceased criminals mostly, though your Death was also very vocal. Well then. You've done me a favour and I don't suppose you did it out of the kindness of your heart. I'll grant you one favour. I suppose you want your Death back?"

Sherlock sucks in a breath and smiles. "Not quite."

The woman leads him back to into the narrow stone tunnels.

"Now understand me," she says. "You'll have to find your own way back to the world of the living."

"Won't be a problem," Sherlock says, confident in his powers of memory. The woman smiles at him.

"You mustn't look back," she says. "One turn of the head, one glance, one word spoken and the thread between the two of you will snap. He won't be able to follow you anymore. Do you understand?"

"I understand."

"Only once you cross your own threshold you will you be safe. Until then, I wouldn't turn around," the woman says, then adds in a lower voice. "I wish you the very best of luck, Sherlock Holmes."

Sherlock begins the walk slowly into the dark tunnels, his senses straining. He can't hear anything except the distant trickling of water and his own footsteps. Or can he? He pauses. Was that another footstep, close behind his own or was just an echo? The back of his neck prickles and he longs to turn around and check. What if the old woman lied to him? What if John wasn't following and her promise was just a lie to get him to leave? Worse- what if the thing behind him isn't John but something else entirely?

Sherlock clenches his fists, takes a deep breath and forces himself onwards, through the winding passages, right, left, right, … Sherlock stops in his tracks. What next? His mind is unaccountably blank. He'd memorised the route but somehow now it escapes him.

_John will know_, his mind reminds him. _All you have to do is turn around and ask_.

The water sounds a little louder in the right hand passage, Sherlock decides. That must be the correct way then, surely? Hoping against hope Sherlock turns right. As he follows it the sounds of the river grow louder and louder until at last he is out into the main chamber with the water rushing past his feet.

Sherlock isn't sure how he will manage to get out if the narrow opening against the current but to his surprise as soon as he steps into the river the water slows to a trickle and dries up. Sherlock clambers out of the cave opening and jumps down onto dry ground with a sense of relief, feeling the brush of the breeze and the warmth of sunlight on his face. He picks up his coat from under the boulder and puts on his shoes, all while carefully not turning his head to look back at the mountain, and at the river which has started to gurgle again.

When he stands and begins the walk back across the moor he notices his shadow, black against the sunlit heather. A single shadow, his own. Nothing to indicate that there is anything or anyone behind him. Sherlock screws his eyes tight shut for a moment, desperately trying to drown out the voice that says _you have to know. You have to find out. Look back._

The sun rises in the sky as Sherlock crosses the moor and then retraces the journey he'd taken with Sebastian – through high mountain passes, past desert wastes, though bustling city streets. He sleeps when he needs to, bundled up in his coat but eats nothing.

He hadn't been sure with Sebastian at which point he crossed from his own world into the in-between but he is quite certain of the crossing place this time because the place he arrives is London. He can hear the buzz of traffic and the jumble of tourists speaking in a dozen languages echoing through the stifling air of the desert before he steps out of that world and onto Westminster Bridge. The wind sweeps over the Thames and ruffles his hair. He wants to laugh, wants to turn to John and see if the same joy and relief is reflected on his face, but he checks himself just in time.

He passes a man selling caramelised peanuts and suddenly remembers that he hasn't eaten for days. He buys himself a bag and wolfs down sweet burning mouthfuls of it as he walks. As he turns out of the less crowded tourist path and into quieter roads he becomes aware of the unmistakeable sound of footsteps on tarmac – footsteps not his own. Sherlock pauses for a moment and the footsteps stop too. _John_.

Or perhaps Sherlock is being followed. A criminal who'd spotted him and decided to take pre-emptive strike at him. Or one of Mycroft's lackeys tailing him with less finesse than usual. He could turn and look and then he'd know for sure.

Sherlock takes a shuddering breath and keeps on walking.

As Sherlock crosses Bloomsbury the sky begins to darken, street lamps blinking onto life. As he reaches the far end of Baker Street he notices his shadow, flung out onto the street by the yellow street light – and behind it another shadow, the image of a shorter man with head bent low, hands stuffed in his coat. Two sets of footsteps echo distinctly as Sherlock climbs the seventeen steps up to his rooms, and opens the door.

He walks to the window first of all, waiting until he's heard the door slowly click shut and the footsteps behind him shift into the middle of the room. Then he turns around.

John is standing in the middle of the room, looking around at the flat with curious eyes. He's changed, of course, skin no longer grey but a light tan colour, eyes dark blue. Only his hair is still grey, though flecked with a muted golden brown.

John shifts to look at himself in the mantelpiece over the mirror, touching his hands to his cheeks, self consciously ruffling through his hair. Then he turns to look at Sherlock. There's a long silence as John simply stares at him, expression unreadable.

"Welcome back," Sherlock says, at last.

"You made me human," John says.

"Yes."

"I didn't ask to be made human, Sherlock."

Sherlock falters for a moment, then says. "You didn't like being my Death."

John looks at him for a long moment, and then expression softens a little.

"You know I wouldn't have wanted to be anyone else's," he says. "I liked taking care of you. Liked working with you."

"You could still do that," Sherlock says. John raises his eyebrows at that as if Sherlock has said something presumptuous, which he probably has. "Or – you can leave. If you want to. It wouldn't hurt. You aren't tied to me anymore."

John takes in a deep breath, looks at the ceiling and lets it out slowly. "That was awful, you know. What you did to me."

"I know."

"You could have told me what you were planning."

"You're too honest, John. I was afraid your face would give the game away," Sherlock says, then adds in a lower voice. "Or that you would try to stop me."

"And then you half-killed yourself coming to get me," John says. "After you promised you'd be more careful with yourself. God knows what could have happened to you out there. I wouldn't trust any Death of James Moriarty's to guide you to the bog let alone the afterlife."

"He wasn't too bad."

John looks down into the fireplace for a moment, away from Sherlock.

"They were pretty thrilled to be reunited, you know. Even Moriarty seemed pleased, which was a weird thing to witness I can tell you. I suppose – that was kind of you. To do that."

"I didn't do it for them."

"I know," John mimicked Sherlock's tone. "_Obviously_."

Sherlock looks at John uncertainly. John sighs deeply and squares his shoulders, turning to look at Sherlock. "I'm not going to leave. Of course I'm not."

Sherlock lets out a breath of relief and gives John a tentative smile and takes a step towards him, reaching out one hand to him.

"John."

John tenses, leaning away.

Sherlock immediately stops. "It isn't dangerous anymore."

"Isn't deadly, you mean," John says.

"Yes."

John looks at Sherlock, eyes wide then looks down again. "I know, I just-"

"Please, John."

John sighs and squares his shoulders, raising his head. "All right."

Sherlock steps forward slowly until he's standing directly in front of John, enjoying being caught in the steady beam of his gaze. Something in his eyes shifts as Sherlock raises his hand again but he doesn't flinch or make to move away. Sherlock places the hand on John's cheek, tracing the line of his jaw with his fingers. He can feel the faint rasp of stubble, the smoothness of the skin under it. He moves to take measure of the pulse jumping in John's neck, the very human vulnerability of flesh and skin.

"Well," John says, a little drily. "Was it worth it?"

"Yes," Sherlock replies and John blinks, a peculiar look passing across his face as if that really hadn't been the answer he'd expected.

"Christ," he says, "You are a madman." And before Sherlock knows it John's arms are on his shoulders, pulling him down into his arms.

"Mmmph," he says, as he gets a face full of John's hair, and shifts a little to render the position more comfortable. John's hand curls around the back of his neck and Sherlock takes a breath of him. He smells of the moor, a faint honey smell underwritten with grass and a faint tang of sweat. John breathes out unevenly against Sherlock's shoulder, head turned so that Sherlock can't see his face.

"What happens to us now?" John asks, in a muffled voice after a few moments.

"Hmm?"

"I can't guide you now I'm human. What will happen when we die? Do we have new Deaths?"

"Hmm," says Sherlock, "I expect so. Or perhaps some other provision will be made. The woman I spoke to seemed efficient. I've no doubt she has a plan. Besides – I don't plan for that to be a relevant eventuality for quite some time now. I want to live for a very long time now I have you here with me."

John pulls back a little and looks up at him, eyes unexpectedly soft. His hand tightens slightly on the nape of Sherlock's neck, guiding his face down towards his and then gently he leans up to press him mouth against Sherlock's. Sherlock's eyes flutter shut to focus on the sensation of soft lips against his and the sweet intimacy of John's breath brushing over his face. When he opens his eyes, John is smiling at him.

"Perhaps," says John, optimistically. "We'll just have to live forever."

Sherlock laughs.


End file.
